Multiple actuator system for solar tracker

ABSTRACT

A solar tracking system is provided and includes a solar array, a support structure configured to support the solar array, a base configured to rotatably support the support structure, and an articulation system configured to articulate the support structure relative to the base. The articulation system includes a gearbox that is coupled to the support structure and an actuator that is configured to extend and retract. The actuator includes a first end portion and a second, opposite end portion, wherein the first end portion is rotatably coupled to the base and the second end portion is coupled to the gearbox. Extension of the actuator causes the support structure to rotate about the base in a first direction and retraction of the actuator causes the support structure to rotate about the based in a second, opposite direction.

BACKGROUND Technical Field

The present disclosure relates to solar power generation systems, andmore particularly, to solar tracker actuating systems for adjusting theorientation of the solar power generation components to track thelocation of the sun.

Background of Related Art

Solar cells and solar panels are most efficient in sunny conditions whenoriented towards the sun at a certain angle. Many solar panel systemsare designed in combination with solar trackers, which follow the sun'strajectory across the sky from east to west in order to maximize theelectrical generation capabilities of the systems. The relatively lowenergy produced by a single solar cell requires the use of thousands ofsolar cells, arranged in an array, to generate energy in sufficientmagnitude to be usable, for example as part of an energy grid. As aresult, solar trackers have been developed that are quite large,spanning hundreds of feet in length.

Adjusting massive solar trackers requires power to drive the solar arrayas it follows the sun. As will be appreciated, the greater the load, thegreater the amount of power necessary to drive the solar tracker. Anadditional design constraint of such systems is the rigidity required toaccommodate the weight of the solar arrays and at times significant windloading.

Further, the torsional excitation caused by wind loading exertssignificant force upon the structure for supporting and the mechanismsfor articulating the solar tracker. As such, increases in the size andnumber of components to reduce torsional excitation are required atvarying locations along the length of the solar tracker. The presentdisclosure seeks to address the shortcomings of prior tracker systems.

SUMMARY

The present disclosure is directed to a solar tracking system includinga solar array, a support structure configured to support the solararray, a base configured to rotatably support the support structure, andan articulation system configured to articulate the support structurerelative to the base. The articulation system includes a gearbox coupledto the support structure and an actuator that is configured to extendand retract. The actuator includes a first end portion and a second,opposite end portion. The first end portion of the actuator is rotatablycoupled to the base and the second end portion is coupled to thegearbox. Extension of the actuator causes the support structure torotate about the base in a first direction and retraction of theactuator causes the support structure to rotate about the base in asecond, opposite direction.

In aspects, the articulation system may include a motor that ismechanically coupled to the gearbox. Actuation of the motor causes theactuator to extend or retract.

In certain aspects, the solar tracking system may include a plurality ofbases, each base rotatably supporting a portion of the supportstructure.

In other aspects, the solar tracking system may include a plurality ofarticulation systems corresponding to a respective base of the pluralityof bases.

In certain aspects, the solar tracking system may include a plurality ofdriveshafts interconnecting the plurality of articulation systems suchthat rotation of the plurality of driveshafts causes a respectiveactuator associated with each articulation system of the plurality ofarticulation systems to extend or retract in unison.

In other aspects, the solar tracking system may include a motor that ismechanically coupled to the plurality of driveshafts. Actuation of themotor causes each driveshaft of the plurality of driveshafts to rotate,which in turn, causes each actuator of the plurality of articulationsystems to extend or retract in unison.

In aspects, each articulation system of the plurality of articulationsystems may include a motor that is mechanically coupled to eachrespective gearbox of the plurality of articulation systems, whereineach motor is configured to actuate a respective actuator of theplurality of articulation systems in unison.

In certain aspects, the gearbox may include an input shaft, a yokerotatably supported by an outer casing of the gearbox, and an idlershaft. An outer surface of the idler shaft defines a transverse boretherethrough that is configured to receive the input shaft therein.

In aspects, the solar tracking system may include a pair of supportbushings coupled to the support structure, wherein the support bushingsare configured to rotatably support the input shaft of the gearbox. Thepair of support bushings enables the gearbox to rotate about an axisdefined by the input shaft but inhibit axial translation of the gearboxrelative to the input shaft.

In other aspects, the second end portion of the actuator may berotatably coupled to the yoke, wherein the yoke permits rotation of theactuator in a direction along the axis defined by the input shaftwithout causing a corresponding rotation of the gearbox.

In aspects, the gearbox may include an input gear fixedly coupled to theinput shaft, an idler gear rotatably supported on the idler shaft, and adriven gear fixedly coupled to the second portion of the actuator,wherein rotation of the input gear causes a corresponding rotation ofthe idler gear, which in turn, causes rotation of the driven gear tocause the actuator to increase or decrease in length.

In certain aspects, the actuator may include a body portion, a nutcoupled to the body portion, and a power screw threadably coupled to thenut, wherein rotation of the power screw relative to the nut cause thepower screw to retract or advance within the body portion.

In other aspects, the support structure may be rotatably supported onthe base at a geometric center of rotation of the support structure.

In certain aspects, the support structure may be rotatably supported onthe base at a center of mass of the support structure and the solararray.

In accordance with another aspect with the present disclosure, a methodof articulating a solar tracking system is provided and includesidentifying a position of the sun relative to the solar array disposedin a support structure, the support structure rotatably supported by aplurality of bases, and changing a length of a plurality of actuatorsassociated with the plurality of bases, wherein rotation of the solararray corrects the orientation of the solar array relative to the sun.

In aspects, changing the length of the plurality of actuators mayinclude causing a motor mechanically coupled to a gearbox associatedwith the plurality of actuators to rotate, wherein rotation of the motorcauses the gearbox to change the length of the plurality of actuators.

In other aspects, changing the length of the plurality of actuators mayinclude causing a motor coupled to a plurality of driveshafts to cause aplurality of gearboxes associated with a respective actuator of theplurality of actuators to rotate, wherein rotation of the motor causesthe plurality of driveshafts to rotate, which in turn, causes theplurality of gearboxes to change the length of the plurality ofactuators.

In certain aspects, changing the length of the plurality of actuatorsmay include causing a plurality of motors coupled to a respectiveplurality of gearboxes associated with the plurality of actuators torotate, wherein rotation of the plurality of motors causes eachrespective gearbox to change the length of each respective actuator ofthe plurality of actuators.

In other aspects, the method may include accommodating thermal expansionof the plurality of driveshafts by permitting a yoke associated with thegearbox to rotate in a direction along an axis defined by the pluralityof driveshafts.

In aspects, accommodating thermal expansion of the plurality ofdriveshafts may include the gearbox including an input shaft and anidler shaft, an outer surface of the idler shaft defining a transversebore configured to receive a portion of the input shaft therethroughsuch that the yoke and idler shaft may rotate relative to the inputshaft in the direction along the axis defined by the plurality ofdriveshafts.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects and features of the present disclosure are describedhereinbelow with reference to the drawings, wherein:

FIG. 1 is a top, perspective view of a solar tracking system provided inaccordance with the present disclosure configured to articulate theangle of a solar array to track the location of the sun;

FIG. 2 is a side view of the solar tracking system of FIG. 1;

FIG. 3 is a bottom, perspective view of the solar tracking system ofFIG. 1;

FIG. 4 is an enlarged view of the area of detail indicated in FIG. 3;

FIG. 4A is an enlarged view of the area of detail indicated in FIG. 4;

FIG. 5 is a top, perspective view of an articulation system of the solartracking system of FIG. 1;

FIG. 6 is a top, perspective view of an actuator of the articulationsystem of FIG. 5 shown coupled to the solar tracking system of FIG. 1;

FIG. 7 is an enlarged view of the area of detail indicated in FIG. 6;

FIG. 8 is a side view of the actuator of FIG. 6 shown coupled to thesolar tracking system of FIG. 1;

FIG. 9 is a perspective view of the actuator of FIG. 6;

FIG. 10 is a perspective view of the actuator of FIG. 6 shown with anouter casing of a gearbox of the actuator of FIG. 6 in phantom;

FIG. 11 is a front view of the actuator of FIG. 6 shown with the outercasing of the gearbox of the actuator of FIG. 6 in phantom;

FIG. 12 is a top view of the actuator of FIG. 6 shown with the outercasing of the gearbox of the actuator of FIG. 6 in phantom;

FIG. 13 is a bottom view of the actuator of FIG. 6 shown with the outercasing of the gearbox of the actuator of FIG. 6 in phantom;

FIG. 14 is a perspective view of a nut of the actuator of FIG. 6; and

FIG. 15 is a graphical representation of the drive torque required toarticulate a solar array of the solar tracking system of FIG. 1 througha range of motion.

DETAILED DESCRIPTION

The present disclosure is directed to solar tracking systems and methodsfor articulating a solar tracking system. The solar tracking systemincludes a solar array that is supported by a support structure. Thesupport structure, in turn, is rotatably supported by a plurality ofbases that are configured to be anchored in the ground or to astationary structure. An articulation system is coupled to the supportstructure and enables the selective rotation of the solar array aboutthe base to track the location of the sun. The articulation systemincludes an actuator that is coupled to a gearbox, the actuator beingrotatably coupled to the base and the gearbox being rotatably coupled tothe support structure. The solar tracking system includes a plurality ofarticulation systems where each articulation system is associated with arespective base. As can be appreciated, using multiple actuatorsprovides additional support to the solar array to reduce twist andreduce the size of components used in the solar tracking system.

The solar tracking system may include a single motor to drive theplurality of articulation systems or may include a plurality of motorsassociated with respective articulation system. Where only one motor isused, a plurality of driveshafts interconnects each gearbox such thatthe motor may drive each actuator simultaneously. To reduce windup andinhibit buckling of each driveshaft, one or more brackets are coupled tothe support structure or solar array which supports the driveshafts atcertain intervals. The plurality of driveshafts may be retained orremoved where there is a plurality of motors employed by the solartracking system. In this manner, each motor is electrically coupled toone another to ensure actuation of the plurality of articulation systemsoccurs in unison to inhibit twist of the support structure or solararray.

The gearbox includes an outer casing, an input shaft which is rotatablysupported by the outer casing, a yoke which is rotatably supported bythe outer casing in a transverse direction to the input shaft, and anidler shaft that is supported by the yoke. An outer surface of the idlershaft includes a transverse bore that is capable of receiving the inputshaft therein. The actuator is rotatably supported at a first end by thebase and the second end of the actuator is coupled to the yoke. Usingthis construction, the articulation system is able to accommodatethermal expansion of the support structure. Specifically, as the supportstructure expands and contracts, the location of the input shaftchanges. To accommodate this change in location, the yoke is permittedto rotate in a direction along the driveshaft. The transverse boreincludes an inner dimension that is large enough to accommodate±10° ofrotation by the actuator relative to the driveshafts. In this manner,the first portion of the actuator may remain stationary while the secondportion of the actuator may be offset relative thereto, which helpsinhibit any bind or stresses that may build up as a result of thethermal expansion of the driveshaft.

The support structure may be rotatably supported at either the geometriccenter of rotation or the center of mass of the support structure andsolar array combined. Rotatably supporting the support structure at isgeometric center of rotation introduces an unbalanced load as thesupport structure is rotated about the base. Specifically, the amount oftorque required to articulate the support structure increases as thesupport structure is rotated from an angled position relative to thebase to a horizontal position relative to the base. By rotatablysupporting the support structure at the center of mass of the supportstructure and solar array combined, the torque required to rotate thesupport structure remains relatively constant through the range ofmotion of the solar tracking system. This reduces the energy required toarticulate the support structure and may reduce the number of differingcomponents, as the components no longer have to be designed for theunbalanced load.

Embodiments of the present disclosure are now described in detail withreference to the drawings in which like reference numerals designateidentical or corresponding elements in each of the several views. In thedrawings and in the description that follows, terms such as front, rear,upper, lower, top, bottom, and similar directional terms are used simplyfor convenience of description and are not intended to limit thedisclosure. In the following description, well-known functions orconstructions are not described in detail to avoid obscuring the presentdisclosure in unnecessary detail.

With reference to FIGS. 1-5, a solar tracking system capable of trackingthe location of the sun provided in accordance with the presentdisclosure is illustrated and generally identified by reference numeral10. The solar tracking system 10 includes a solar array 20, a supportstructure 30 that is configured to support the solar array 20, a base 40that is configured to rotatably support the support structure 30, and anarticulation system 100 (FIG. 2) that is configured to articulate thesolar array 20 and support structure 30 relative to the base 40. Thesolar array 20 includes a plurality of photovoltaic modules 22, each ofwhich is mechanically and electrically coupled to one another, althoughit is contemplated that each photovoltaic module 22 may be mechanicallyand/or electrically insulated from one another. In embodiments, thephotovoltaic modules 22 may be any suitable photovoltaic module capableof generating electrical energy from sunlight, such as monocrystallinesilicon, polycrystalline silicon, thin-film, etc. The photovoltaicmodules 22 define an upper surface 22 a and an opposite, bottom surface22 b. As can be appreciated, the upper surface 22 a of the photovoltaicmodules 22 includes the photovoltaic cells (not shown) while the bottomsurface 22 b includes any suitable means for fixedly or selectivelycoupling the photovoltaic modules 22 to the support structure 30, suchas mechanical fasteners (e.g., bolts, nuts, etc.), adhesives, welding,etc, although it is envisioned that the photovoltaic modules 22 may bebi-facial photovoltaic modules, in which case the bottom surface 22 bmay also include photovoltaic cells such that energy may be capturedfrom both the upper and bottom surfaces 22 a, 22 b.

In embodiments, the photovoltaic cells may be disposed within a suitableframe (not shown) which includes suitable means for fastening thephotovoltaic modules 22 to the support structure 30. In this manner, theframe may include fastening means on a bottom surface thereof (notshown), or clamps or other suitable fasteners (e.g., Z-brackets,C-clamps, angle brackets, etc.) may be utilized to abut a portion of theframe and selectively or fixedly couple the frame to the supportstructure 30.

The support structure 30 includes a pair of parallel beams 32 (FIG. 3)disposed in spaced relation to one another and extending along a lengthof the solar tracking system 10. Although generally illustrated as beinga C-channel, it is contemplated that the pair of parallel beams 32 maybe any suitable beam capable of supporting the solar array 20, such asbox beams, I-beams, H-beams, circular or round beams, etc. Inembodiments, each beam of the pair of parallel beams 32 may include thesame profile or may include different profiles, depending upon theinstallation needs of the solar tracking system 10.

With additional reference to FIG. 6, the support structure 30 includespairs of transverse beams 34 defining opposed ends 34 a and 34 b (FIG.3). The pairs of transverse beams 34 are disposed parallel to oneanother and are spaced apart to receive a portion of the base 40, suchthat the support structure 30 may articulate without the base 40interfering with articulation of the support structure 30 relativethereto, as will be described in further detail hereinbelow. Althoughgenerally illustrated as being a C-channel, it is contemplated that thepair of transverse beams 34 may be any suitable beam capable ofsupporting the solar array 20, such as box beams, I-beams, H-beams, etc.In embodiments, each beam of the pairs of transverse beams 34 mayinclude the same profile or may include different profiles, dependingupon the installation needs of the solar tracking system 10.

Each end of the opposed ends 34 a, 34 b of the pairs of transverse beams34 is coupled to a respective beam of the pair of parallel beams 32. Inthis manner, an end cap 36 is disposed adjacent to each end 34 a or 34 bof each beam of the pair of transverse beams 34. The end cap 36 definesa generally planar surface 36 a extending between opposed side surfaces36 b and top and bottom surfaces 36 c. Although generally illustrated ashaving rectangular outer profile, other suitable profiles arecontemplated, such as square, hexagonal, circular, oval, etc. The planarsurface 36 a defines a bore 36 d therethrough. Although generallyillustrated as having a profile corresponding to the outer profile ofthe planar surface 36 a, it is contemplated that the profile of the bore36 d may be any suitable profile, such as square, hexagonal, circular,oval, etc. and may be different than the profile of the planar surface36 a. The planar surface 36 a defines a first pair of flanges 36 edisposed adjacent the opposed side surfaces 36 b and extending betweenthe top and bottom surfaces 36 c (FIG. 6). The planar surface 36 adefines a second pair of flanges 36 f disposed adjacent the bore 36 dand oriented parallel to the first pair of flanges 36 e such that achannel 36 g is defined between each of the first and second pairs offlanges 36 e, 36 f. The channels 36 g are configured to receive acorresponding end 34 a, 34 b of each beam of the pair of transversebeams 34 such that the pair of transverse beams 34 may be coupled to thefirst and second pair of flanges 36 e, 36 f using any suitable means,such as mechanical fasteners, adhesives, welding, or the like.

Although illustrated as having a distance between the top and bottomsurfaces 36 c that is greater than the height of the pair of parallelbeams 32, it is contemplated that the cap 36 may have a distance betweenthe top and bottom surfaces 36 c that is the same as or less than theheight of the pair of parallel beams 32. With continued reference toFIG. 6, the cap 36 is fixedly or selectively coupled to each respectivebeam of the pair of parallel beams using any suitable means, such asmechanical fasteners, adhesives, welding, etc.

With reference to FIGS. 4 and 6, the base 40 defines a generallyC-shaped profile, although it is contemplated that the base may be anysuitable beam capable of supporting the solar array 20 and the supportstructure 30, such as box beams, I-beams, H-beams, etc. The base 40extends between a first end portion 40 a configured to be anchored inthe ground and an opposite, second end portion 40 b configured torotatably support the support structure 30. In this manner, a pivotassembly 50 (FIG. 6) is coupled to the second end portion 40 a andincludes a support 52, a pivot 54, a pivot pin 56, and a pair ofbrackets 58. The support 52 defines a generally C-shaped profiledefining a planar portion 52 a and a pair of opposed flanges 52 bdisposed on opposing end portions thereof. The pair of opposed flanges52 b is spaced apart such that the second end portion 40 a of the base40 is interposed therebetween and the planar portion 52 a abuts thesecond end portion 40 a, although it is contemplated that planar portion52 a of the support 52 may be spaced apart from the second end portion40 a of the base. The pair of opposed flanges 52 b is fixedly orselectively coupled to the second end portion 40 a using any suitablemeans, such as mechanical fasteners, adhesives, welding, etc. Anactuator mounting flange 42 (FIG. 4) is disposed on an outer surface ofthe base 40 adjacent to the first end portion 40 a. It is contemplatedthat the actuator mounting flange 42 may be fixedly or selectivelycoupled to the base 40 using any suitable means, such as mechanicalfasteners, adhesives, welding, etc. Although generally illustrated asdefining a generally C-shaped profile, it is contemplated that theactuator mounting flange 42 may define any suitable profile, such assquare, rectangular, etc. In this manner, the actuator mounting flange42 defines a pair of opposed flanges 42 a extending from a planarsurface that is coupled to the outer surface of the base 40. Inembodiments, the actuator mounting flange 42 may include a pair ofindependent flanges 42 a that are individually coupled to the outersurface of the base 40. The pair of opposed flanges 42 a defines a bore42 b therethrough that is configured to enable a pin (not shown) orother suitable means for rotatably coupling a portion of thearticulation system 100 thereto when a portion of the articulationsystem 100 is interposed between the pair of opposed flanges 42 a.

The pivot 54 defines a generally C-shaped profile having a planarportion 54 a and a pair of opposed flanges 54 b extending therefrom.Although generally illustrated as having a triangular profile, it iscontemplated that the pair of opposed flanges 54 b may include anysuitable profile such as square, rectangular, oval, etc. In embodiments,each flange of the pair of opposed flanges 54 b may have the sameprofile or a different profile. The pair of opposed flanges 54 b definea corresponding pair of through-holes 54 c therethrough that areconfigured to receive the pivot pin 56 therein.

As illustrated in FIG. 6, when the pivot pin 56 is received within thepair of opposed flanges 54 b, the pivot pin 56 extends beyond eachflange of the pair of opposed flanges 54 b to engage a respectivebracket of the pair of brackets 58. The pivot pin 56 defines a generallycylindrical profile extending between opposed end surfaces 56 a. Eachend surface of the opposed end surfaces 56 a defines a relief (notshown) therein and extending toward one another. In this manner, theopposed end surfaces 56 a define a generally D-shaped profile, althoughany suitable profile that is capable of inhibiting rotation of the pivotpin 56 relative to the pair of brackets 58 is contemplated, such ashexalobe, oval, square, rectangular, etc.

The pair of brackets 58 defines a generally C-shaped profile having aplanar portion 58 a and a pair of opposed flanges 58 b extendingtherefrom. Although generally illustrated as having a triangularprofile, it is contemplated that the pair of opposed flanges 58 b mayinclude any suitable profile, such as square, rectangular, oval, etc. Inembodiments, each flange of the pair of opposed flanges 58 b may havethe same profile or a different profile. The pair of opposed flangesdefines a corresponding pair of through-bores (not shown) therethroughthat are configured to fixedly receive the pivot pin 56 therein. In thismanner, each through-hole of the pair of through-holes defines a profilethat is complementary to that of the profile of each corresponding endsurface of the opposed end surfaces 56 a of the pivot pin. As can beappreciated, the matching profiles of the through-holes and the opposedend surfaces 56 a ensure that each bracket of the pair of brackets 58remains aligned with one another to minimize or eliminate twisting ofthe support structure 30 (e.g., torque applied to one end surface istransferred through the pivot pin 56 to the opposite end surface of theopposed end surfaces 56 a. In embodiments, the pivot pin 56 may notinclude a D-shaped profile an can be coupled to the pair of brackets 58by friction fit, staking, adhesives, mechanical fasteners, welding, etc.The planar portion 58 a is configured to be fixedly or selectivelycoupled to a corresponding beam of the pairs of transverse beams 34 torotatably couple the support structure 30 to the base 40.

With additional reference to FIG. 7, the support structure 30 includes apair of shear plates 38 having a generally L-shaped profile, althoughother suitable profiles are contemplated, such as C-shaped, etc. In thismanner, each shear plate 38 includes a generally planar portion 38 a anda flange 38 b disposed at an end portion thereof and extendingperpendicular therefrom. As can be appreciated, the flange 38 b isconfigured to abut an upper portion of a corresponding beam of the pairsof transverse beams 34. The planar portion 38 a defines a hole 38 ctherethrough that is configured to receive a bearing or bushing of thearticulation system 100, as will be described in further detail below.As illustrated in FIG. 7, the pair of shear plates 38 is disposed inopposed relation to one another on a respective beam of the pairs oftransverse beams 34.

Turning now to FIGS. 7-14, the articulation system 100 is illustratedand includes an actuator 102 and a gearbox 120. The actuator 102includes a tubular body 106, a nut 108, a power screw 110, and a heimjoint assembly 112. The tubular body 106 of the actuator 102 extendsbetween opposed end surfaces 106 a and 106 b. Although generallyillustrated as having a cylindrical profile, it is contemplated that thetubular body 106 may include any suitable profile, such as square,rectangular, oval, hexagonal, etc. The opposed end surfaces 106 a, 106 bdefine a through-hole 106 c therethrough that is configured to receivethe nut 108 adjacent the end surface 106 a and a heim joint assembly 112adjacent the end surface 106 b. The nut 108 (FIG. 14) includes a washer108 a and a body portion 108 b. The washer 108 a defines a generallyplanar configuration having a generally circular profile correspondingto the profile of the tubular body 106. As can be appreciated, thewasher 108 a may include any suitable profile and may include the sameor different profile than the tubular body 106. The washer 108 a definesa through-hole 108 c therethrough that is configured to receive aportion of the body portion 108 b therethrough. The washer 108 a iscoupled to the end surface 106 a of the tubular body 106 using anysuitable means, such as mechanical fasteners, friction fit, adhesives,welding, etc.

The body portion 108 b of the nut 108 defines a generally cylindricalprofile having an outer diameter generally the same as an outer diameterof the tubular body 106, although other suitable configurations arecontemplated. The body portion 108 b extends between opposed endsurfaces 108 d and 108 e. The end surface 108 e defines an annularrelief 108 f therein extending towards the end surface 108 d and throughan outer surface 108 g of the nut 108. The annular relief 108 fterminates in a face 108 g oriented opposite to the end surface 108 dand is configured to abut a portion of the washer 108 a. Althoughillustrated as being selectively coupled to the washer 108 a usingmechanical fasteners (i.e., bolts, screws, etc.), it is contemplatedthat the body portion 108 b of the nut 108 may be selectively coupled tothe washer 108 a using any suitable means, and in embodiments, may befixedly coupled to the washer 108 a using any suitable means, such asadhesives, friction fit, welding, etc. The opposed end surfaces 108 d,108 e of the body portion 108 b define a threaded bore 108 htherethrough that is configured to threadably engage the power screw110, such that the power screw 110 can translate therewithin whenrotated in a first or second direction relative to the nut 108, as willbe described in further detail hereinbelow.

With reference to FIGS. 9-11, the heim joint assembly 112 includes aheim joint washer 112 a, a heim joint 112 b, and a heim joint nut 112 c.The heim joint washer 112 a extends between opposed end surfaces 112 eand 112 f and defines a generally cylindrical profile that iscomplimentary to the profile of the tubular body 106, although it iscontemplated that the profile of the heim joint washer 112 a may includeany suitable profile, such as square, rectangular, oval, etc. The endsurface 112 e is configured to abut end surface 106 b of the tubularbody and may be selectively or fixedly coupled thereto using anysuitable means, such as mechanical fasteners, friction fit, adhesives,welding, etc. The opposed end surfaces 112 e, 112 f define a threadedbore 112 g therethrough that is configured to threadably engage aportion of the heim joint 112 b.

The heim joint 112 b may be any suitable articulating joint and includesan articulating head portion 112 h and a threaded shank 112 i (FIG. 11)extending therefrom. The threaded shank 112 i is configured tothreadably engage the threaded bore 112 g of the heim joint washer 112 asuch that the heim joint 112 b may translate within the heim jointwasher 112 a when the heim joint 112 b is rotated. In this manner, theoverall length of the actuator 102 can be increased or decreased byrotating the heim joint 112 b in a first direction or second, oppositedirection. The head portion 112 h of the heim joint 112 b defines alumen 112 j therethrough that is configured to receive a suitablefastener (e.g., bolt, pin, etc.) therein to rotatably couple the heimjoint 112 b, and thereby the actuator 102, to the actuator mountingflange 42 (FIG. 2) of the base 40.

The heim joint nut 112 c is threadably coupled to the threaded shank 112i of the heim joint 112 b. The heim joint nut 112 c is configured to actas a jam nut such that when the heim joint nut 112 c is threaded in afirst direction, the heim joint nut 112 c abuts the end surface 112 f ofthe heim joint washer 112 a, and further rotation of the heim joint nut112 c in the first direction tightens the heim joint nut 112 c againstthe end surface 112 f of the heim joint washer 112 a to lock theposition of the heim joint 112 b relative to the heim joint washer 112a. To loosen the heim joint nut 112 c, the heim joint nut 112 c isrotated in a second, opposite direction.

Although generally described as being a heim joint, it is contemplatedthat the heim joint 112 b may be any suitable articulating joint, andmay be integrally formed with the actuator tube 106 or the heim jointwasher 112 a. In embodiments, the heim joint 112 b may be a ball bearing(stainless steel, bronze, brass, polymer, etc.) or a bushing (brass,bronze, polymer, etc.).

In embodiments, the articulation system 100 may not utilize a heim jointassembly 112. Rather, an outer surface 106 d of the tubular body 106defines a transverse bore (not shown) that is configured to receive asuitable fastener (e.g., bolt, pin, etc.) therein to rotatably couplethe tubular body 106, and thereby the actuator 102, to the actuatormounting flange 42 of the base 40.

The power screw 110 extends between a first end surface 110 a and anopposite, second end surface 110 b and defines a threaded outer surface110 c therebetween. The threaded outer surface 110 c includes athreadform that is complimentary to that of the nut 108 such that thepower screw 110 may threadably engage the threaded bore 108 h of the nut108. In this manner, as the power screw 110 is rotated in a firstdirection, the overall length of the actuator 102 increases and as thepower screw 110 is rotated in a second, opposite direction, the overalllength of the actuator 102 decreases. As will be described in furtherdetail hereinbelow, the increase or decrease in the overall length ofthe actuator 102 causes articulation of the support structure 30 andsolar array 20 about the pivot pin 56 of the pivot assembly 50 (FIG. 6).

The threaded outer surface 110 c of the power screw 110 may define anysuitable threadform (e.g., square, trapezoidal, buttress, etc.) capableof supporting and transmitting large loads, although other threadformsare also contemplated, such as triangular threadforms (e.g., uniformthread standard, etc.). In embodiments, the power screw 110 may be aball screw, a glidescrew, a leadscrew, etc. In one non-limitingembodiment, the threaded outer surface 110 c of the power screw 110defines a trapezoidal threadform such as an acme threadform and hasself-locking or anti-backdrive properties sufficient to inhibit thepower screw 110 from rotating under the static weight of the solar array20, support structure 30, and various components of the articulationsystem 100 that are supported by the power screw 110. Additionally, theanti-backdrive properties of the power screw 110 inhibit the power screwfrom rotating when an external force is applied to the solar trackingsystem 10, such as wind, snow, wildlife, etc. The first end surface 110a is configured to couple to a portion of the gearbox 120 such that arotational force imparted on the gearbox 120 is transmitted to the powerscrew 110, as will be described in further detail hereinbelow.

The gearbox 120 includes an outer casing 122 and a gear train 126. Theouter casing 122 (FIG. 9) defines a body 128 and a cover 130. The body128 defines a generally square profile extending between opposed endsurfaces 128 a and 128 b. The end surface 128 a defines a cavity 128 ctherein terminating at an inner surface 128 d. The inner surface 128 dand the opposed end surface 128 b define a through-bore 128 etherethrough that is configured to receive a portion of the power screw110 therein. As will be described in further detail hereinbelow, thethrough-bore 128 e is dimensioned to permit articulation of the powerscrew 110 relative to the body 122 without causing interference (e.g.,the power screw 110 is permitted to pivot relative to the body 122).

The body 128 defines a first pair of opposed side surfaces 128 k and 128f and a second pair of opposed side surfaces 128 g and 128 h disposedtransverse to the first pair of opposed side surfaces 128 k, 128 f Eachof the side surfaces of the first pair of opposed side surfaces 128 k,128 f define a through-hole 128 i therethrough that is configured torotatably support a portion of an input shaft 132 therethrough and eachof the side surfaces of the second pair of opposed side surfaces 128 g,128 h defines a bore 128 j (FIG. 9) therethrough that is configured tosupport a portion of an idler shaft 134 therein, as will be described infurther detail hereinbelow. The cover 130 is configured to selectivelycouple to the end surface 128 a using any suitable means, such asmechanical fasteners, adhesives, friction fit, etc.

The gear train 126 includes an input shaft 132, an idler shaft 134, apair of support bushings 136, a drive gear 138, an idler gear 140, adriven gear 142, and a yoke 144. The input shaft 132 defines a generallycylindrical profile extending between a first end portion 132 a and anopposite second end portion 132 b. An outer surface 132 c of the inputshaft 132 defines a hole 132 d adjacent each of the first and second endportions 132 a, 134 b that is configured to selectively receive a pin(not shown) or other suitable device capable of rotatably supporting andlongitudinally fixing a drive shaft 150 (FIG. 7) of the solar trackingsystem 10, as will be described in further detail hereinbelow. The inputshaft 132 is configured to be rotatably supported within thethrough-hole 128 i of the first pair of opposed side surfaces 128 e, 128f using any suitable means, such as a bushing, bearing, etc.

The idler shaft 134 defines a generally cylindrical profile extendingbetween opposed end portions 134 a and 134 b. An outer surface 134 c ofthe idler shaft defines a transverse bore 134 d therethrough at a centerportion thereof (e.g., approximately the middle of the idler shaft 134).The transverse bore 134 d extends through the idler shaft 134perpendicular to an axis A-A defined through the length (e.g., throughthe opposed end portions 134 a, 134 b) of the idler shaft 134 and isconfigured to receive a portion of the input shaft 132 therein. Thetransverse bore 134 d is dimensioned such that the input shaft 132 mayrotate about the axis A-A approximately 10 degrees in either direction(e.g., ±10°) without the input shaft 132 impacting any portion of thetransverse bore 134 d (e.g., the transverse bore 134 d includes an innerdimension that is larger than an outer dimension of the input shaft132), as will be described in further detail hereinbelow.

The pair of support bushings 136 defines a generally cylindrical profileextending between a first end surface 136 a and a second, opposite endsurface 136 b. Each bushing of the pair of support bushings 136 issubstantially similar, and therefore, only one support bushing 136 willbe described in detail herein in the interest of brevity. The first endsurface 136 a defines an annular relief 136 c extending through an outersurface of the support bushing 136 and extending towards the second endsurface 136 b. The annular relief 136 c terminates at an annular face136 d having an outer dimension that is greater than the outer dimensionof the annular relief. The second end surface 136 b defines a firstcounterbore 136 e therein extending towards the first end surface 136 aand terminating at an annular face 136 f. The annular face 136 f of thefirst counterbore 136 e defines a boss 136 g extending therefrom andprotruding past the second end surface 136 b and terminating at a thirdend surface 136 h. An outer surface of the boss 136 g is configured tobe received within the through-hole 128 i of the outer casing 122 suchthat the outer casing 122 is rotatably supported thereon. The third endsurface 136 h and the first end surface 136 a of the support bushing 136define a through-bore (not shown) therethrough that is configured torotatably support a portion of the input shaft 132 therein. The firstend surface 136 a defines a second counterbore 136 j therein.

Although generally described as being a one-piece bushing (e.g., asingle component), it is contemplated that the support bushing 136 maybe formed from more than one component and in one non-limitingembodiment, may be a bearing with a bushing, a bearing with an extendedinner race (e.g., roller bearing, ball bearing, etc.), etc. As can beappreciated, the annular face 136 d of the support bushing 136 isconfigured to abut a portion of a respective shear plate 38 of thesupport structure 30 to inhibit the support bushing 136 from entirelypassing through a hole 38 c of the shear plate 38. In this manner, theannular face 136 d locates the support bushing 136 relative to thegearbox 134.

The yoke 144 defines a generally U-shaped profile having a planarsurface 146 and opposed tabs 148 extending therefrom (FIG. 7). Althoughgenerally illustrated as having a triangular profile, it is contemplatedthat the opposed tabs 148 may include any suitable profile, and each tabmay be the same or include different profiles. The planar surface 146defines a bore (not shown) therethrough configured to receive a portionof the power screw 110 therein. It is contemplated that the bore mayinclude a suitable bearing, bushing, etc. (not shown) or in embodiments,may not include a bearing or bushing but rather at least one thrustbearing or bushing (not shown) may be disposed adjacent the planarsurface 146 and concentric to the bore. The opposed tabs 148 define athrough-hole (not shown) therethrough that is configured to support aportion of the idler shaft 134 therein. In embodiments, the through-holeis dimensioned to fixedly retain the idler shaft 134 therein, such thatthe idler shaft 134 is inhibited from rotating about the axis A-A,although it is contemplated that the idler shaft 134 may freely rotatewithin the through-hole of the opposed tabs 148. Where the idler shaft134 is fixedly retained within the through-hole, it is contemplated thatthe idler shaft 134 maybe fixedly retained using any suitable means,such as friction fit, keys, splines, adhesives, etc. Each of the opposedtabs 148 defines a boss 148 a thereon that is concentric with thethrough-hole. Each boss of pair of bosses 148 a is configured to bereceived within a respective the bore 128 j of the outer casing 122 ofgearbox 128 such that each bore 128 j rotatably supports each respectiveboss 148 a to enable the yoke 144 to rotate about an axis defined by theidler shaft 134.

The drive gear 138 is supported on the input shaft 132 and is coupledthereto using any suitable means, such as a clamp, friction fit, pins,etc., such that rotation of the input shaft 132 causes a correspondingrotation of the drive gear 138. Although generally shown as a bevelgear, it is contemplated that the drive gear 138 may be any suitabledevice capable of transmitting rotational motion from the input shaft132 to the idler gear 140, and in one non-limiting embodiment, the drivegear 138 may be a face-gear or the like.

The idler gear 140 is rotatably supported on the idler shaft 134 suchthat the idler gear 140 is free to rotate relative to the idler shaft134 using any suitable means, such as a bushing, bearing, etc. The idlergear 140 is sized and dimensioned such that a portion of the idler gear140 is able to mesh with the drive gear 138 and a portion of the idlergear 140 is able to mesh with the driven gear 142. Although generallyillustrated as being a bevel gear, it is contemplated that the idlergear 140 may be any suitable device capable of transmitting rotationalmotion from the drive gear 138 to the driven gear 142.

The driven gear 142 is fixedly retained on a portion of the power screw110 adjacent the first end surface 110 a thereof using any suitablemeans, such as a clamp, friction fit, pins, etc., such that rotation ofthe driven gear 142 causes a corresponding rotation of the power screw110. Although generally illustrated as being a bevel gear, it iscontemplated that the driven gear 142 may be any suitable device capableof transmitting rotational motion from the idler gear 140 to the powerscrew 110. As can be appreciated, the driven gear 142 clamps the powerscrew 110 to the yoke 144 such that the power screw 110, and thus thedriven gear 142, is inhibited from translating relative to the yoke 144.

In embodiments, it is contemplated that the location of each of thedrive gear 138, the idler gear 140, the driven gear 142, the pair ofsupport bushings 136, and idler shaft 134 may be translatably fixedusing circlips, e-clips, pins, adhesives, welding, etc. In this manner,the relative location of each of the drive gear 138, idler gear 140,driven gear, the pair of support bushings 136, and idler shaft 134 maybe fixed relative to one another to ensure proper engagement of each ofthe drive gear 138, the idler gear 140, and the driven gear 142 duringoperation of the articulation system 100. In embodiments, it iscontemplated that any of the drive gear 138, idler gear 140, and drivengear 142 may be a face gear or the like.

It is contemplated that the gearbox 120 may not include a yoke 144, andrather the idler shaft 134 may be supported by the body 128 of thegearbox 120. In this manner, the body 128 of the gearbox supports theupper portion of the power screw 110, and the driven gear 142 clamps thepower screw 110 to the body 128.

Returning to FIG. 3, the solar tracking system 10 includes anarticulation system 100 disposed at each base 40, although it iscontemplated that the solar tracking system 10 may include only onearticulation system 100, an articulation system 100 may be disposed atevery other base 40, or any other suitable pattern depending upon theinstallation needs of the solar tracking system 10. The placement of anarticulation system 100 at each base 40 reduces the load eacharticulation system 100 is required to support. As a consequence, theoverall size of the components of the articulation system 100 can bereduced, thereby saving materials and cost. Additionally, using multiplearticulation systems 100 increases the overall stiffness of the solartracking system 10 by reducing the distance between each point at whichan articulation system 100 is placed, thereby reducing the torsionalloading on the support structure 30, amongst other benefits. Further,using multiple actuation systems 100 reduces the need for the pivot pin56 of the support structure 30 to be placed at the center of gravity ofthe support structure 30 and solar array 20 assemblies.

As illustrated in FIG. 15, placement of the pivot pin 56 at thegeometric center of rotation of the solar array 20 and support structure30 assembly may cause an unbalanced load as the support structure 30 isarticulated by the actuation assemblies 100. Specifically, when in aninitial, east facing orientation, the amount of drive torque required torotate the support structure 30 about the pivot pin 56 is relativelylow. However, as the support structure is further rotated, the torquerequired to rotate the support structure 30 increases until the supportstructure 30 is placed in an approximately horizontal orientation.Continued rotation of the support structure 30 towards the west requiresa diminishing amount of torque as the center of gravity of the solararray 20 and support structure 30 assembly migrates closer to thegeometric center of rotation.

To diminish the effects of this unbalanced load, it is contemplated thatthe pivot pin 56 may be disposed at the center of mass of the solararray 20 and support structure 30 assembly rather than the geometriccenter of rotation. In this manner, the mass of the solar array 20 andsupport structure 30 is balanced about the pivot pin 56 and the torquerequired to articulate the support structure 30 about the pivot pin 56remains substantially consistent, with little to no variation in thetorque required to articulate the support structure through its range ofmotion. As such, the amount of energy required to articulate the supportstructure 30 is reduced and the various components required to supportthe solar array 20 may be substantially similar (e.g., no need to designcertain components to take a larger load than others), thereby reducingdesign time and reducing the number of differing components in the solartracking assembly 10. As can be appreciated, each solar array 20 mayinclude a differing amount of wiring, actuatotion systems 100, driveshafts 150, etc. which necessarily means that each solar array 20 mayinclude a different weight than one another. By shifting the axis ofrotation from the geometric center of rotation to the center of mass,each solar array may include a different axis of rotation, which inturn, reduces unbalanced loads placed upon the articulation system 100.

In order to transfer the torque between each articulation system 100, aplurality of drive shafts 150 (FIGS. 3, 4A, 6, and 7) are disposed onthe support structure 30 and coupled to a respective input shaft 134 ofa respective gearbox 120. By locating the plurality of drive shafts 150on the support structure 30, each base 40 may remain identical, therebyreducing the number of variations of the base 40 required to constructthe solar tracking system 10. It is contemplated that each of theplurality of drive shafts 150 may be rotatably supported by a bracket152 (FIG. 4A), such as a pillow block, heim joint, bushing, etc., thatis disposed on the bottom surface 22 b of the photovoltaic modules 22 orthe frame (not shown) of the photovoltaic modules 22. The outerdimension of the drive shaft 150 and the number of brackets 152 may varydepending on the installation needs of the solar tracking system 10. Ascan be appreciated, the larger the outer dimension of the drive shaft150 and a greater number of brackets 152 increases the torsional loadcapacity of the drive shaft 150 while minimizing wind-up or twist in thedrive shaft and reducing the proclivity of the drive shaft 150 to buckleunder torsional load.

The bracket 152 inhibits buckling of the drive shaft 150 over itslength, and therefore, enables a reduction in the overall diameter andwall thickness of the drive shaft 150 required to transfer a particularload without wind-up or buckling. In this manner, it is contemplatedthat one or more brackets 152 may be utilized. In one non-limitingembodiment, two brackets 152 are utilized to support the drive shaft 150at intervals of one third of the overall length of the drive shaft 150.

During fluctuations in temperature, the overall length of each solararray 20 may increase or decrease due to thermal expansion orcontraction of the various components thereof. As can be appreciated,the location at which the gearbox 120 secures to the driveshaft 150 mayvary due to the dimensional changes driven by thermal expansion orcontraction of the driveshaft and/or support structure 30. Toaccommodate this fluctuation, the yoke 144 is rotatably supported withinthe outer casing 122 of the gearbox 120 about the longitudinal axis A-A.As such, as the support structure 30 expands and contracts and thegearbox 120 is caused to translate transverse to the actuator mountingflange 42 of the base 40, the actuator 102, via the heim joint 112 b, ispermitted to rotate about the fastener coupling the heim joint 112 b tothe mounting flange 42. The transverse bore 134 d of the idler shaft 134provides clearance for the input shaft 132 to pass therethrough withoutinterference as the yoke 144, and therefore the idler shaft 134, rotatesabout the axis A-A. Further, the support bushings 38 inhibit the outercasing 122 of the gearbox 120 from rotating relative to the driveshaft150 to inhibit binding or misalignment between the input shaft 132 ofthe gearbox 120 and the driveshaft 150.

With reference again to FIG. 4, the articulation system 100 includes amotor 160 and an associated motor gear box 162. The motor 160 may be anysuitable motor capable of transmitting rotational motion to the driveshaft 150, such as an alternating current (AC) motor, a direct current(DC) motor, a servo, a stepper motor, etc. In one non-limitingembodiment, the motor 160 is a brushless direct current (DC) motor. Themotor 160 is coupled to the gear box 162 using any suitable means, suchas mechanical fasteners, adhesives, welding, etc. In turn, the gear box162 is coupled to the support structure 30 using any suitable means,such as mechanical fasteners, adhesives, welding, etc. It iscontemplated that the gear box 162 may be any suitable gearbox capableof transmitting rotational motion from the motor 160 to the drive shaft150, such as a constant mesh gear box, belts and pulleys, sprockets andchains, friction wheels, hydraulic, etc.

Continuing with FIG. 4, it is contemplated that each articulation system100 may include a respective motor 160 and gear box 162, or inembodiments, only one motor 160 and gearbox 162 may be utilized. In thismanner, a motor 160 and/or gearbox 162 may be placed at any base 40(regardless of the presence of an articulation system 100) and therotational torque supplied by the motor 160 will be transferred to eacharticulation system 100 via the plurality of drive shafts 150. In onenon-limiting embodiment, the motor 160 and gearbox 162 may be placed atan outer-most base 40. In embodiments, the motor 160 may be placed atany base 40 and may directly drive the plurality of drive shafts 150without the use of the gearbox 162. As can be appreciated, utilizingmultiple motors 160 reduces the size of the motor required to producethe appropriate amount of torque to articulate the support structure 30.Similarly, utilizing a gear box 162 reduces the size of the motor 160required to produce the appropriate amount of torque to articulate thesupport structure 30. Further still, utilizing multiple motors 160enables smaller and lighter drive shafts 150 to be utilized and reducesthe number of brackets 152 that are required to inhibit buckling of thedrive shafts 150, and in embodiments, may eliminate the need for thedrive shafts 150 altogether.

In embodiments, each actuation system 100 may include a positive stop(not shown) or other similar device capable of inhibiting over extensionthereof and to limit any damaged caused therefrom. As can beappreciated, the positive stop for each individual actuation system 100may be calibrated to inhibit actuation of any one actuation system 100relative to one another to a certain degree to minimize torsional loadsand/or misalignment between adjacent solar arrays 20.

Referring again to FIGS. 1-13, a method of articulating a solar trackingsystem 10 is described. Initially, each actuation system 100 iscalibrated to ensure that the position of each actuator 102 of the solartracking system 10 is substantially the same. Placing each actuator 102in the substantially same position reduces the amount of twist of thesolar array 20. In embodiments, each actuation assembly 100 may includea positive stop to ensure the actuator 102 does not over extend anddamage components of the solar tracking system 10.

After identifying the position of the sun, a signal is transmitted froma suitable controller to the motor or motors 160 to rotate the powerscrew 110. If the sun is traveling in an east to west direction (e.g.,daylight into twilight), the signal causes the motor 160 to rotate in afirst direction, thereby causing the power screw 110 to rotate in acorresponding first direction to increase the overall length of theactuator 102. Increasing the length of the actuator 102 causes thesupport structure 30 to rotate clockwise about the pivot pin 56 andcause the solar array 20 to rotate in a corresponding clockwisedirection. To set the position of the solar array 20, the signal causesthe motor 160 to rotate in a second direction, opposite to the firstdirection, thereby causes the power screw 110 to rotate in acorresponding second direction that is opposite to the first directionto decrease the overall length of the actuator 102.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of particular embodiments.

What is claimed is:
 1. A solar tracking system, comprising: a solararray; a support structure including a pair of parrallel beams extendingalong a longitudinal axis of the solar tracking system and a pair oftransverse beams substantially perpendicular to and affixed to theparallel beams, the support structure being configured to support thesolar array; a base received between the pair of transverse beams andconfigured to rotatably support the support structure; and anarticulation system configured to articulate the support structurerelative to the base, the articulation system comprising: a gearboxcoupled between the pair of transverse beams of the support structure;an actuator having a first end portion and an second, opposite endportion, wherein the first end portion is rotatably coupled to the baseand the second end portion is coupled to the gearbox, the actuatorconfigured to extend and retract, wherein extension of the actuatorcauses the support structure to rotate about the base in a firstdirection and retraction of the actuator causes the support structure torotate about the base in a second, opposite direction; and a drive shaftmounted in the support structure, traversing the transverse beams, andoperably connected to the gearbox such that rotation of the drive shaftextends and retracts the actuator.
 2. The solar tracking systemaccording to claim 1, wherein the articulation system includes a motorthat is mechanically coupled to the gearbox via the drive shaft, whereinactuation of the motor causes the actuator to extend or retract.
 3. Thesolar tracking system according to claim 1, further including aplurality of bases, each base rotatably supporting a portion of thesupport structure.
 4. The solar tracking system according to claim 3,further including a plurality of articulation systems corresponding to arespective base of the plurality of bases.
 5. The solar tracking systemaccording to claim 4, further including a plurality of driveshaftsinterconnecting the plurality of articulation systems such that rotationof the plurality of driveshafts causes a respective actuator associatedwith each articulation system of the plurality of articulation systemsto extend or retract in unison.
 6. The solar tracking system accordingto claim 5, further including a motor that is mechanically coupled tothe plurality of driveshafts, wherein actuation of the motor causes eachdriveshaft of the plurality of driveshafts to rotate, which in turn,causes each actuator of the plurality of articulation systems to extendor retract in unison.
 7. The solar tracking system according to claim 4,wherein each articulation system of the plurality of articulationsystems includes a motor that is mechanically coupled to each respectivegearbox of the plurality of articulation systems, wherein each motor isconfigured to actuate a respective actuator of the plurality ofarticulation systems in unison.
 8. The solar tracking system accordingto claim 1, wherein the gearbox includes an input shaft, a yokerotatably supported by an outer casing of the gearbox, and an idlershaft, an outer surface of the idler shaft defining a transverse boretherethrough that is configured to receive the input shaft therein. 9.The solar tracking system according to claim 8, further including a pairof support bushings coupled to the support structure, wherein thesupport bushings are configured to rotatably support the input shaft ofthe gearbox, the pair of support bushings enabling the gearbox to rotateabout an axis defined by the input shaft but inhibit axial translationof the gearbox relative to the input shaft.
 10. The solar trackingsystem according to claim 9, wherein the second end portion of theactuator is rotatably coupled to the yoke, wherein the yoke permitsrotation of the actuator in a direction along the axis defined by theinput shaft without causing a corresponding rotation of the gearbox. 11.The solar tracking system according to claim 10, wherein the gearboxincludes an input gear fixedly coupled to the input shaft, an idler gearrotatably supported on the idler shaft, and a driven gear fixedlycoupled to the second portion of the actuator, wherein rotation of theinput gear causes a corresponding rotation of the idler gear, which inturn, causes rotation of the driven gear to cause the actuator toincrease or decrease in length.
 12. The solar tracking system accordingto claim 1, wherein the actuator includes a body portion, a nut coupledto the body portion, and a power screw threadably coupled to the nut,wherein rotation of the power screw relative to the nut causes the powerscrew to retract or advance within the body portion.
 13. The solartracking system according to claim 1, wherein the support structure isrotatably supported on the base at a geometric center of rotation of thesupport structure.
 14. The solar tracking system according to claim 1,wherein the support structure is rotatably supported on the base at acenter of mass of the support structure and the solar array.